3 * Copyright (c) 2006 The Regents of The University of Michigan
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7 * modification, are permitted provided that the following conditions are
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15 * this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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35 * Definition of a simple bus bridge without buffering.
40 #include "base/trace.hh"
41 #include "mem/bridge.hh"
42 #include "sim/builder.hh"
44 Bridge::BridgePort::BridgePort(const std::string
&_name
,
45 Bridge
*_bridge
, BridgePort
*_otherPort
,
46 int _delay
, int _nack_delay
, int _req_limit
,
47 int _resp_limit
, bool fix_partial_write
)
48 : Port(_name
), bridge(_bridge
), otherPort(_otherPort
),
49 delay(_delay
), nackDelay(_nack_delay
), fixPartialWrite(fix_partial_write
),
50 outstandingResponses(0), queuedRequests(0), inRetry(false),
51 reqQueueLimit(_req_limit
), respQueueLimit(_resp_limit
), sendEvent(this)
55 Bridge::Bridge(Params
*p
)
57 portA(p
->name
+ "-portA", this, &portB
, p
->delay
, p
->nack_delay
,
58 p
->req_size_a
, p
->resp_size_a
, p
->fix_partial_write_a
),
59 portB(p
->name
+ "-portB", this, &portA
, p
->delay
, p
->nack_delay
,
60 p
->req_size_b
, p
->resp_size_b
, p
->fix_partial_write_b
),
61 ackWrites(p
->write_ack
), _params(p
)
64 panic("No support for acknowledging writes\n");
68 Bridge::getPort(const std::string
&if_name
, int idx
)
72 if (if_name
== "side_a")
74 else if (if_name
== "side_b")
79 if (port
->getPeer() != NULL
)
80 panic("bridge side %s already connected to.", if_name
);
88 // Make sure that both sides are connected to.
89 if (portA
.getPeer() == NULL
|| portB
.getPeer() == NULL
)
90 fatal("Both ports of bus bridge are not connected to a bus.\n");
92 if (portA
.peerBlockSize() != portB
.peerBlockSize())
93 fatal("Busses don't have the same block size... Not supported.\n");
97 Bridge::BridgePort::respQueueFull()
99 assert(outstandingResponses
>= 0 && outstandingResponses
<= respQueueLimit
);
100 return outstandingResponses
>= respQueueLimit
;
104 Bridge::BridgePort::reqQueueFull()
106 assert(queuedRequests
>= 0 && queuedRequests
<= reqQueueLimit
);
107 return queuedRequests
>= reqQueueLimit
;
110 /** Function called by the port when the bus is receiving a Timing
113 Bridge::BridgePort::recvTiming(PacketPtr pkt
)
115 DPRINTF(BusBridge
, "recvTiming: src %d dest %d addr 0x%x\n",
116 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr());
118 DPRINTF(BusBridge
, "Local queue size: %d outreq: %d outresp: %d\n",
119 sendQueue
.size(), queuedRequests
, outstandingResponses
);
120 DPRINTF(BusBridge
, "Remove queue size: %d outreq: %d outresp: %d\n",
121 otherPort
->sendQueue
.size(), otherPort
->queuedRequests
,
122 otherPort
->outstandingResponses
);
124 if (pkt
->isRequest() && otherPort
->reqQueueFull() && pkt
->result
!=
126 DPRINTF(BusBridge
, "Remote queue full, nacking\n");
131 if (pkt
->needsResponse() && pkt
->result
!= Packet::Nacked
)
132 if (respQueueFull()) {
133 DPRINTF(BusBridge
, "Local queue full, no space for response, nacking\n");
134 DPRINTF(BusBridge
, "queue size: %d outreq: %d outstanding resp: %d\n",
135 sendQueue
.size(), queuedRequests
, outstandingResponses
);
139 DPRINTF(BusBridge
, "Request Needs response, reserving space\n");
140 ++outstandingResponses
;
143 otherPort
->queueForSendTiming(pkt
);
149 Bridge::BridgePort::nackRequest(PacketPtr pkt
)
152 pkt
->result
= Packet::Nacked
;
153 pkt
->setDest(pkt
->getSrc());
155 //put it on the list to send
156 Tick readyTime
= curTick
+ nackDelay
;
157 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
, true);
159 // nothing on the list, add it and we're done
160 if (sendQueue
.empty()) {
161 assert(!sendEvent
.scheduled());
162 sendEvent
.schedule(readyTime
);
163 sendQueue
.push_back(buf
);
167 assert(sendEvent
.scheduled() || inRetry
);
169 // does it go at the end?
170 if (readyTime
>= sendQueue
.back()->ready
) {
171 sendQueue
.push_back(buf
);
175 // ok, somewhere in the middle, fun
176 std::list
<PacketBuffer
*>::iterator i
= sendQueue
.begin();
177 std::list
<PacketBuffer
*>::iterator end
= sendQueue
.end();
178 std::list
<PacketBuffer
*>::iterator begin
= sendQueue
.begin();
181 while (i
!= end
&& !done
) {
182 if (readyTime
< (*i
)->ready
) {
184 sendEvent
.reschedule(readyTime
);
185 sendQueue
.insert(i
,buf
);
195 Bridge::BridgePort::queueForSendTiming(PacketPtr pkt
)
197 if (pkt
->isResponse() || pkt
->result
== Packet::Nacked
) {
198 // This is a response for a request we forwarded earlier. The
199 // corresponding PacketBuffer should be stored in the packet's
200 // senderState field.
201 PacketBuffer
*buf
= dynamic_cast<PacketBuffer
*>(pkt
->senderState
);
203 // set up new packet dest & senderState based on values saved
204 // from original request
205 buf
->fixResponse(pkt
);
207 // Check if this packet was expecting a response and it's a nacked
208 // packet, in which case we will never being seeing it
209 if (buf
->expectResponse
&& pkt
->result
== Packet::Nacked
)
210 --outstandingResponses
;
213 DPRINTF(BusBridge
, "restoring sender state: %#X, from packet buffer: %#X\n",
214 pkt
->senderState
, buf
);
215 DPRINTF(BusBridge
, " is response, new dest %d\n", pkt
->getDest());
220 if (pkt
->isRequest() && pkt
->result
!= Packet::Nacked
) {
226 Tick readyTime
= curTick
+ delay
;
227 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
);
228 DPRINTF(BusBridge
, "old sender state: %#X, new sender state: %#X\n",
229 buf
->origSenderState
, buf
);
231 // If we're about to put this packet at the head of the queue, we
232 // need to schedule an event to do the transmit. Otherwise there
233 // should already be an event scheduled for sending the head
235 if (sendQueue
.empty()) {
236 sendEvent
.schedule(readyTime
);
238 sendQueue
.push_back(buf
);
242 Bridge::BridgePort::trySend()
244 assert(!sendQueue
.empty());
246 PacketBuffer
*buf
= sendQueue
.front();
248 assert(buf
->ready
<= curTick
);
250 PacketPtr pkt
= buf
->pkt
;
252 // Ugly! @todo When multilevel coherence works this will be removed
253 if (pkt
->cmd
== MemCmd::WriteInvalidateReq
&& fixPartialWrite
&&
254 pkt
->result
!= Packet::Nacked
) {
255 PacketPtr funcPkt
= new Packet(pkt
->req
, MemCmd::WriteReq
,
257 funcPkt
->dataStatic(pkt
->getPtr
<uint8_t>());
258 sendFunctional(funcPkt
);
259 pkt
->cmd
= MemCmd::WriteReq
;
263 DPRINTF(BusBridge
, "trySend: origSrc %d dest %d addr 0x%x\n",
264 buf
->origSrc
, pkt
->getDest(), pkt
->getAddr());
266 bool wasReq
= pkt
->isRequest();
267 bool wasNacked
= pkt
->result
== Packet::Nacked
;
269 if (sendTiming(pkt
)) {
271 sendQueue
.pop_front();
272 buf
->pkt
= NULL
; // we no longer own packet, so it's not safe to look at it
274 if (buf
->expectResponse
) {
275 // Must wait for response
276 DPRINTF(BusBridge
, " successful: awaiting response (%d)\n",
277 outstandingResponses
);
279 // no response expected... deallocate packet buffer now.
280 DPRINTF(BusBridge
, " successful: no response expected\n");
288 --outstandingResponses
;
291 // If there are more packets to send, schedule event to try again.
292 if (!sendQueue
.empty()) {
293 buf
= sendQueue
.front();
294 DPRINTF(BusBridge
, "Scheduling next send\n");
295 sendEvent
.schedule(std::max(buf
->ready
, curTick
+ 1));
298 DPRINTF(BusBridge
, " unsuccessful\n");
301 DPRINTF(BusBridge
, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
302 sendQueue
.size(), queuedRequests
, outstandingResponses
);
307 Bridge::BridgePort::recvRetry()
310 Tick nextReady
= sendQueue
.front()->ready
;
311 if (nextReady
<= curTick
)
314 sendEvent
.schedule(nextReady
);
317 /** Function called by the port when the bus is receiving a Atomic
320 Bridge::BridgePort::recvAtomic(PacketPtr pkt
)
322 // fix partial atomic writes... similar to the timing code that does the
323 // same... will be removed once our code gets this right
324 if (pkt
->cmd
== MemCmd::WriteInvalidateReq
&& fixPartialWrite
) {
326 PacketPtr funcPkt
= new Packet(pkt
->req
, MemCmd::WriteReq
,
328 funcPkt
->dataStatic(pkt
->getPtr
<uint8_t>());
329 otherPort
->sendFunctional(funcPkt
);
331 pkt
->cmd
= MemCmd::WriteReq
;
333 return delay
+ otherPort
->sendAtomic(pkt
);
336 /** Function called by the port when the bus is receiving a Functional
339 Bridge::BridgePort::recvFunctional(PacketPtr pkt
)
341 std::list
<PacketBuffer
*>::iterator i
;
342 bool pktContinue
= true;
344 for (i
= sendQueue
.begin(); i
!= sendQueue
.end(); ++i
) {
345 if (pkt
->intersect((*i
)->pkt
)) {
346 pktContinue
&= fixPacket(pkt
, (*i
)->pkt
);
351 otherPort
->sendFunctional(pkt
);
355 /** Function called by the port when the bus is receiving a status change.*/
357 Bridge::BridgePort::recvStatusChange(Port::Status status
)
359 otherPort
->sendStatusChange(status
);
363 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList
&resp
,
366 otherPort
->getPeerAddressRanges(resp
, snoop
);
369 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge
)
371 Param
<int> req_size_a
;
372 Param
<int> req_size_b
;
373 Param
<int> resp_size_a
;
374 Param
<int> resp_size_b
;
376 Param
<Tick
> nack_delay
;
377 Param
<bool> write_ack
;
378 Param
<bool> fix_partial_write_a
;
379 Param
<bool> fix_partial_write_b
;
381 END_DECLARE_SIM_OBJECT_PARAMS(Bridge
)
383 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge
)
385 INIT_PARAM(req_size_a
, "The size of the queue for requests coming into side a"),
386 INIT_PARAM(req_size_b
, "The size of the queue for requests coming into side b"),
387 INIT_PARAM(resp_size_a
, "The size of the queue for responses coming into side a"),
388 INIT_PARAM(resp_size_b
, "The size of the queue for responses coming into side b"),
389 INIT_PARAM(delay
, "The miminum delay to cross this bridge"),
390 INIT_PARAM(nack_delay
, "The minimum delay to nack a packet"),
391 INIT_PARAM(write_ack
, "Acknowledge any writes that are received."),
392 INIT_PARAM(fix_partial_write_a
, "Fixup any partial block writes that are received"),
393 INIT_PARAM(fix_partial_write_b
, "Fixup any partial block writes that are received")
395 END_INIT_SIM_OBJECT_PARAMS(Bridge
)
397 CREATE_SIM_OBJECT(Bridge
)
399 Bridge::Params
*p
= new Bridge::Params
;
400 p
->name
= getInstanceName();
401 p
->req_size_a
= req_size_a
;
402 p
->req_size_b
= req_size_b
;
403 p
->resp_size_a
= resp_size_a
;
404 p
->resp_size_b
= resp_size_b
;
406 p
->nack_delay
= nack_delay
;
407 p
->write_ack
= write_ack
;
408 p
->fix_partial_write_a
= fix_partial_write_a
;
409 p
->fix_partial_write_b
= fix_partial_write_b
;
410 return new Bridge(p
);
413 REGISTER_SIM_OBJECT("Bridge", Bridge
)